The present disclosure relates generally to pigment-based inks.
Electronic inks are commonly used in electronic displays. Such electronic inks often include charged colorant particles that, in response to an applied electric field, rearrange within a viewing area of the display to produce desired images. This effect is known as electrophoresis, or more broadly electrokinetics.
Electronic inks are useful as a medium to low power reflective types of displays. Conventional electrophoretic displays feature either black and white states (by exchanging white and black charged colorant particles at the top of the display cell) or white and colored states (by moving white colorant particles in a dyed fluid up and down electrophoretically). These conventional electrophoretic displays cannot provide a clear state and cannot be easily extended to provide full-color displays with bright colors. There remain, however, technical challenges in identifying ink components that can stably operate in the electrophoretic/electrokinetic regime.
Many current approaches to achieve full color in low power reflective display rely on combining color filter and a black/white switching electronic ink. However, this reduces lightness and chroma for the end devices.
To achieve full color with bright images, the use of stacked device architecture based on the principle of printing with subtractive CMYK pigments has been developed. This new architecture requires a completely new design of novel electronic inks, which need to be switched between clear and color states. Many of the colored inks so far have not shown good compaction and/or spreading of the pigments upon application of an electric field.